Process for desulphurizing hot metal

Abstract

The invention relates to a process for desulphurizing hot metal in a ladle, in particular in a torpedo ladle, wherein first aluminum and then, by means of a carrier gas, lime (CaO) are blown into the hot metal. The characterizing feature of the invention is that at a rate of 2-20 liters (S.T.P.) of carrier gas/kg of desulphurizing agent, a solid which evolves a gas in the hot metal is blown in together with the lime.

We claim: 
     
       1. A process for desulphurising hot metal in a ladle which comprises adding aluminum to the hot metal, and then blowing into the hot metal a carrier gas containing lime and a compound which decomposes upon contact with the hot metal thereby generating gas. 
     
     
       2. Process according to claim 1, characterised in that the gas-evolving solid added is an alkaline earth metal carbonate and/or a alkaline earth hydrate. 
     
     
       3. Process according to claim 2, characterised in that the alkaline earth metal carbonate blown in is limestone or dolomite and the alkaline earth hydrate blown in is hydrated lime. 
     
     
       4. Process according to claim 1, characterised in that a mixture consisting of 40-70% by weight of lime and 30-60% by weight of gas-evolving solid is blown into the hot metal. 
     
     
       5. Process according to claim 1, characterised in that a proportion of carbon or carbonaceous substances in the range of 1-10% by weight is added to the mixture which is blown in. 
     
     
       6. Process according to claim 1, characterised in that 1-10% by weight of fluorite is added to the mixture which is blown in. 
     
     
       7. Process according to claim 1, characterised in that the conveying rate is 3-8 liters (S.T.P.) of carrier gas/kg of desulphurising agent. 
     
     
       8. Process according to claim 1, characterised in that the mixture is blown into the molten hot metal by means of compressed air. 
     
     
       9. Process according to claim 1, characterised in that aluminum and the desulphurisation mixture is introduced into the hot metal when the hot metal has a temperature of at least 1350° C. 
     
     
       10. Process according to claim 1, wherein 2-20 liters (S.T.P.) of the carrier gas /kg of desulphurising agent is used for blowing the lime and decomposable solid into the hot metal. 
     
     
       11. Process according to claim 1, wherein the ladle is a torpedo ladle.